ISTANBUL: Turkish lawmakers on Thursday brawled and threw chairs as parliament approved three more articles in a hugely controversial bill bolstering the powers of President Recep Tayyip Erdogan.

Lawmakers have since the start of the week been debating the first reading of the 18-article bill to change the constitution to create an executive presidency.

The articles approved covered lowering the minimum age limit of members of parliament from 25 to 18, stipulating parliamentary elections be held every five years, instead of four, and on the parliament's own powers.

Five of the 18 articles have now been approved with the three-fifths majority required for the new constitution to be submitted to a referendum expected in April.

The ruling Justice and Development Party (AKP) has mustered sufficient votes in an alliance with the Nationalist Movement Party (MHP).

But the changes are vehemently opposed by the main opposition Republican People's Party (CHP), whose lawmakers boycotted the vote.

A brawl erupted in the chamber as the voting took place in an overnight session, with lawmakers punching each another and chairs being thrown, television pictures showed.

Dozens of lawmakers crowded around the speaker's rostrum with one MP held in a chokehold and another kicked in the shins.

Another was seen being led away, apparently bleeding from the head, while the lectern from which MPs deliver speeches was also badly damaged in the fracas.

Female MPs meanwhile shook their heads and waved their hands in despair.

- Erdogan confident -

Despite the tensions, all articles have mustered sufficient support so far and Erdogan on Thursday voiced confidence that the draft constitution would be approved by parliament and sent to a referendum.

"Nothing is gained from hindering and delaying the works in the parliament," he said during a meeting with local officials in Ankara.

"No matter what you do... I believe (the draft constitution) will be handed to the people," he said.

Some commentators had suggested that dissent from within the AKP could give the draft bill a rocky ride in the days to come when votes are made on the most contentious articles.

Other key changes will include giving the president the power to name and fire ministers as well as abolishing the post of premier but creating vice presidents.

The two readings are expected to take two weeks, with parliament working without a break. Three more articles will be voted overnight Thursday.

- Snap poll? -

The CHP blamed the AKP for the fighting and said it would stand its ground by maintaining the boycott.

"I am proud of my CHP deputies who showed resistance despite all the attacks from the AKP," the CHP faction's deputy chairman Ozgur Ozel said.

The pro-Kurdish Peoples' Democratic Party (HDP) also boycotted the vote in protest at the arrest of its two co-leaders and several other MPs over alleged links to the outlawed Kurdistan Workers' Party (PKK).

A senior AKP lawmaker, Mustafa Sentop, warned that a failure to pass the draft constitution would push Turkey to a snap election.

"It could be in the spring, autumn or whenever. No one can stop the elections," Sentop told Anadolu news agency.

While critics say the move is part of a power grab by Erdogan for a one-man rule, supporters say it will put Turkey in line with France and the US and is needed for efficient government.

Along with a slew of terror attacks, the political uncertainty has been one of the factors pressuring the Turkish lira, which has slid 18 percent against the dollar over the last three months.